What happens to the total resistance in a series circuit if the resistance of one resistor increases?
A The total resistance decreases
B The total resistance increases
C The total resistance remains the same
D The current increases
In a series circuit, the total resistance is the sum of the individual resistances. If one resistor’s resistance increases, the total resistance will also increase.
What is the total voltage across the components in a parallel circuit?
A It is divided equally among the components
B It is the same across all components
C It is the sum of individual voltages
D It is zero
In a parallel circuit, the voltage across each component is the same as the source voltage, regardless of the resistance of the components.
What is the formula for calculating the total resistance in a parallel circuit with two resistors, R1 and R2?
A R_total = R1 + R2
B R_total = 1 / (1/R1 + 1/R2)
C R_total = R1 * R2
D R_total = (R1 + R2) / 2
The total resistance in a parallel circuit is calculated using the reciprocal formula: 1/R_total = 1/R1 + 1/R2. This gives a total resistance lower than the smallest individual resistance.
What does Kirchhoff’s Current Law (KCL) state?
A The sum of voltages around a closed loop equals zero
B The sum of currents entering a junction equals the sum of currents leaving the junction
C The current in a circuit is constant
D The voltage across resistors is constant
Kirchhoff’s Current Law (KCL) states that the total current entering a junction (or node) in a circuit is equal to the total current leaving that junction, based on the principle of conservation of charge.
What happens to the current in a series circuit if the total resistance is increased?
A The current decreases
B The current increases
C The current stays the same
D The current becomes zero
According to Ohm’s Law (V = I * R), if the total resistance in a series circuit increases, the current will decrease, assuming the voltage remains constant.
What is the relationship between current and voltage in a resistive circuit according to Ohm’s Law?
A Voltage is inversely proportional to current
B Voltage is directly proportional to current
C Voltage is constant
D Current is constant
According to Ohm’s Law, the voltage across a resistor is directly proportional to the current flowing through it, with resistance as the proportionality constant. The formula is **V = I * R**.
How is the total power in an electrical circuit calculated?
A Power = Voltage × Resistance
B Power = Current × Voltage
C Power = Voltage / Current
D Power = Current × Resistance
The total power dissipated in an electrical circuit is given by the formula **P = I * V**, where **I** is the current and **V** is the voltage.
What is the main function of an inductor in an AC circuit?
A To store energy in an electric field
B To store energy in a magnetic field
C To resist changes in voltage
D To convert AC to DC
An **inductor** stores energy in the form of a magnetic field when current flows through it. It resists changes in current and opposes voltage fluctuations.
What is the unit of reactance in an AC circuit?
A Volt
B Ampere
C Ohm
D Henry
The unit of **reactance** (whether inductive or capacitive) is the **ohm (Ω)**, which is the same as resistance. Reactance refers to the opposition to current flow in AC circuits caused by inductance or capacitance.
What is the primary purpose of a capacitor in an electrical circuit?
A To increase current flow
B To store electrical energy in an electric field
C To filter out noise
D To store electrical energy in a magnetic field
A **capacitor** stores electrical energy in an electric field between two conductive plates. It is commonly used to store and release energy and to filter or smooth signals.
What happens to the current in a parallel circuit when more resistors are added?
A The current decreases
B The current increases
C The current stays the same
D The current becomes zero
In a **parallel circuit**, adding more resistors provides additional paths for current to flow, which increases the total current supplied by the source.
What is the unit of inductance?
A Watt
B Volt
C Henry
D Ampere
The unit of **inductance** is the **henry (H)**, which represents the ability of an inductor to oppose changes in current in an AC circuit.
What is the main function of a transformer in an electrical system?
A To store electrical energy
B To increase or decrease voltage
C To control current flow
D To filter out noise
A **transformer** is used to change the voltage level in an AC circuit. It can either **step up** (increase) or **step down** (decrease) the voltage depending on the turns ratio between its coils.
What happens in a DC circuit when the power factor is 1?
A The circuit is inefficient
B The circuit uses all power effectively
C The current is zero
D The voltage is equal to current
A power factor of **1** means that all the power supplied to the circuit is being used effectively, with no power lost due to phase differences between current and voltage.
What is the unit of reactance in an AC circuit?
A Watt
B Ohm
C Volt
D Ampere
The unit of **reactance** (whether inductive or capacitive) is the **ohm (Ω)**, which is the same as resistance. Reactance refers to the opposition to current flow in AC circuits caused by inductance or capacitance.
What is the main function of a feedback mechanism in an electrical circuit?
A To store energy
B To stabilize the circuit’s performance
C To increase power
D To decrease current flow
**Feedback mechanisms** are used to adjust the output of a circuit based on its input, helping to stabilize performance, reduce fluctuations, and improve overall control.
What happens to the voltage in a series circuit if the total resistance increases?
A The voltage decreases
B The voltage increases
C The voltage remains the same
D The voltage becomes zero
In a **series circuit**, if the total resistance increases, the voltage is divided across the resistors, resulting in a drop in the voltage available to each component.
What is the phase difference between current and voltage in a purely inductive AC circuit?
A 0 degrees
B 45 degrees
C 90 degrees (current lags voltage)
D 180 degrees
In a **purely inductive AC circuit**, the **current lags the voltage by 90 degrees**. This phase shift occurs due to the inductive reactance, which resists changes in current.
What happens in an electrical circuit when the power factor is less than 1?
A The circuit uses all power efficiently
B Some of the power is wasted as reactive power
C The current is zero
D The voltage is equal to current
A power factor less than **1** means that some of the power is being lost as reactive power, which does not perform useful work.
What is the primary purpose of a diode in an electrical circuit?
A To amplify the signal
B To allow current to flow in only one direction
C To resist current flow
D To store electrical energy
A **diode** allows current to flow only in one direction, making it useful for converting alternating current (AC) to direct current (DC) in rectification circuits.